1 files changed, 381 insertions, 303 deletions

diff --git a/fs/afs/volume.c b/fs/afs/volume.c
index db73d6dad02b..0efff3d25133 100644
--- a/fs/afs/volume.c
+++ b/fs/afs/volume.c
@@ -1,28 +1,181 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /* AFS volume management
  *
  * Copyright (C) 2002, 2007 Red Hat, Inc. All Rights Reserved.
  * Written by David Howells (dhowells@redhat.com)
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version
- * 2 of the License, or (at your option) any later version.
  */
 
 #include <linux/kernel.h>
-#include <linux/module.h>
-#include <linux/init.h>
 #include <linux/slab.h>
-#include <linux/fs.h>
-#include <linux/pagemap.h>
-#include <linux/sched.h>
 #include "internal.h"
 
-static const char *afs_voltypes[] = { "R/W", "R/O", "BAK" };
+static unsigned __read_mostly afs_volume_record_life = 60 * 60;
+static atomic_t afs_volume_debug_id;
+
+static void afs_destroy_volume(struct work_struct *work);
 
 /*
- * lookup a volume by name
- * - this can be one of the following:
+ * Insert a volume into a cell.  If there's an existing volume record, that is
+ * returned instead with a ref held.
+ */
+static struct afs_volume *afs_insert_volume_into_cell(struct afs_cell *cell,
+						      struct afs_volume *volume)
+{
+	struct afs_volume *p;
+	struct rb_node *parent = NULL, **pp;
+
+	write_seqlock(&cell->volume_lock);
+
+	pp = &cell->volumes.rb_node;
+	while (*pp) {
+		parent = *pp;
+		p = rb_entry(parent, struct afs_volume, cell_node);
+		if (p->vid < volume->vid) {
+			pp = &(*pp)->rb_left;
+		} else if (p->vid > volume->vid) {
+			pp = &(*pp)->rb_right;
+		} else {
+			if (afs_try_get_volume(p, afs_volume_trace_get_cell_insert)) {
+				volume = p;
+				goto found;
+			}
+
+			set_bit(AFS_VOLUME_RM_TREE, &volume->flags);
+			rb_replace_node_rcu(&p->cell_node, &volume->cell_node, &cell->volumes);
+		}
+	}
+
+	rb_link_node_rcu(&volume->cell_node, parent, pp);
+	rb_insert_color(&volume->cell_node, &cell->volumes);
+	hlist_add_head_rcu(&volume->proc_link, &cell->proc_volumes);
+
+found:
+	write_sequnlock(&cell->volume_lock);
+	return volume;
+
+}
+
+static void afs_remove_volume_from_cell(struct afs_volume *volume)
+{
+	struct afs_cell *cell = volume->cell;
+
+	if (!hlist_unhashed(&volume->proc_link)) {
+		trace_afs_volume(volume->debug_id, volume->vid, refcount_read(&volume->ref),
+				 afs_volume_trace_remove);
+		write_seqlock(&cell->volume_lock);
+		hlist_del_rcu(&volume->proc_link);
+		if (!test_and_set_bit(AFS_VOLUME_RM_TREE, &volume->flags))
+			rb_erase(&volume->cell_node, &cell->volumes);
+		write_sequnlock(&cell->volume_lock);
+	}
+}
+
+/*
+ * Allocate a volume record and load it up from a vldb record.
+ */
+static struct afs_volume *afs_alloc_volume(struct afs_fs_context *params,
+					   struct afs_vldb_entry *vldb,
+					   struct afs_server_list **_slist)
+{
+	struct afs_server_list *slist;
+	struct afs_volume *volume;
+	int ret = -ENOMEM, i;
+
+	volume = kzalloc(sizeof(struct afs_volume), GFP_KERNEL);
+	if (!volume)
+		goto error_0;
+
+	volume->debug_id	= atomic_inc_return(&afs_volume_debug_id);
+	volume->vid		= vldb->vid[params->type];
+	volume->update_at	= ktime_get_real_seconds() + afs_volume_record_life;
+	volume->cell		= afs_get_cell(params->cell, afs_cell_trace_get_vol);
+	volume->type		= params->type;
+	volume->type_force	= params->force;
+	volume->name_len	= vldb->name_len;
+	volume->creation_time	= TIME64_MIN;
+	volume->update_time	= TIME64_MIN;
+
+	refcount_set(&volume->ref, 1);
+	INIT_HLIST_NODE(&volume->proc_link);
+	INIT_WORK(&volume->destructor, afs_destroy_volume);
+	rwlock_init(&volume->servers_lock);
+	mutex_init(&volume->volsync_lock);
+	mutex_init(&volume->cb_check_lock);
+	rwlock_init(&volume->cb_v_break_lock);
+	INIT_LIST_HEAD(&volume->open_mmaps);
+	init_rwsem(&volume->open_mmaps_lock);
+	memcpy(volume->name, vldb->name, vldb->name_len + 1);
+
+	for (i = 0; i < AFS_MAXTYPES; i++)
+		volume->vids[i] = vldb->vid[i];
+
+	slist = afs_alloc_server_list(volume, params->key, vldb);
+	if (IS_ERR(slist)) {
+		ret = PTR_ERR(slist);
+		goto error_1;
+	}
+
+	*_slist = slist;
+	rcu_assign_pointer(volume->servers, slist);
+	trace_afs_volume(volume->debug_id, volume->vid, 1, afs_volume_trace_alloc);
+	return volume;
+
+error_1:
+	afs_put_cell(volume->cell, afs_cell_trace_put_vol);
+	kfree(volume);
+error_0:
+	return ERR_PTR(ret);
+}
+
+/*
+ * Look up or allocate a volume record.
+ */
+static struct afs_volume *afs_lookup_volume(struct afs_fs_context *params,
+					    struct afs_vldb_entry *vldb)
+{
+	struct afs_server_list *slist;
+	struct afs_volume *candidate, *volume;
+
+	candidate = afs_alloc_volume(params, vldb, &slist);
+	if (IS_ERR(candidate))
+		return candidate;
+
+	volume = afs_insert_volume_into_cell(params->cell, candidate);
+	if (volume == candidate)
+		afs_attach_volume_to_servers(volume, slist);
+	else
+		afs_put_volume(candidate, afs_volume_trace_put_cell_dup);
+	return volume;
+}
+
+/*
+ * Look up a VLDB record for a volume.
+ */
+static struct afs_vldb_entry *afs_vl_lookup_vldb(struct afs_cell *cell,
+						 struct key *key,
+						 const char *volname,
+						 size_t volnamesz)
+{
+	struct afs_vldb_entry *vldb = ERR_PTR(-EDESTADDRREQ);
+	struct afs_vl_cursor vc;
+	int ret;
+
+	if (!afs_begin_vlserver_operation(&vc, cell, key))
+		return ERR_PTR(-ERESTARTSYS);
+
+	while (afs_select_vlserver(&vc)) {
+		vldb = afs_vl_get_entry_by_name_u(&vc, volname, volnamesz);
+	}
+
+	ret = afs_end_vlserver_operation(&vc);
+	return ret < 0 ? ERR_PTR(ret) : vldb;
+}
+
+/*
+ * Look up a volume in the VL server and create a candidate volume record for
+ * it.
+ *
+ * The volume name can be one of the following:
  *	"%[cell:]volume[.]"		R/W volume
  *	"#[cell:]volume[.]"		R/O or R/W volume (rwparent=0),
  *					 or R/W (rwparent=1) volume
@@ -42,353 +195,278 @@ static const char *afs_voltypes[] = { "R/W", "R/O", "BAK" };
  * - Rule 3: If parent volume is R/W, then only mount R/W volume unless
  *           explicitly told otherwise
  */
-struct afs_volume *afs_volume_lookup(struct afs_mount_params *params)
+struct afs_volume *afs_create_volume(struct afs_fs_context *params)
 {
-	struct afs_vlocation *vlocation = NULL;
-	struct afs_volume *volume = NULL;
-	struct afs_server *server = NULL;
-	char srvtmask;
-	int ret, loop;
-
-	_enter("{%*.*s,%d}",
-	       params->volnamesz, params->volnamesz, params->volname, params->rwpath);
-
-	/* lookup the volume location record */
-	vlocation = afs_vlocation_lookup(params->cell, params->key,
-					 params->volname, params->volnamesz);
-	if (IS_ERR(vlocation)) {
-		ret = PTR_ERR(vlocation);
-		vlocation = NULL;
-		goto error;
-	}
+	struct afs_vldb_entry *vldb;
+	struct afs_volume *volume;
+	unsigned long type_mask = 1UL << params->type;
 
-	/* make the final decision on the type we want */
-	ret = -ENOMEDIUM;
-	if (params->force && !(vlocation->vldb.vidmask & (1 << params->type)))
-		goto error;
+	vldb = afs_vl_lookup_vldb(params->cell, params->key,
+				  params->volname, params->volnamesz);
+	if (IS_ERR(vldb))
+		return ERR_CAST(vldb);
 
-	srvtmask = 0;
-	for (loop = 0; loop < vlocation->vldb.nservers; loop++)
-		srvtmask |= vlocation->vldb.srvtmask[loop];
+	if (test_bit(AFS_VLDB_QUERY_ERROR, &vldb->flags)) {
+		volume = ERR_PTR(vldb->error);
+		goto error;
+	}
 
+	/* Make the final decision on the type we want */
+	volume = ERR_PTR(-ENOMEDIUM);
 	if (params->force) {
-		if (!(srvtmask & (1 << params->type)))
+		if (!(vldb->flags & type_mask))
 			goto error;
-	} else if (srvtmask & AFS_VOL_VTM_RO) {
+	} else if (test_bit(AFS_VLDB_HAS_RO, &vldb->flags)) {
 		params->type = AFSVL_ROVOL;
-	} else if (srvtmask & AFS_VOL_VTM_RW) {
+	} else if (test_bit(AFS_VLDB_HAS_RW, &vldb->flags)) {
 		params->type = AFSVL_RWVOL;
 	} else {
 		goto error;
 	}
 
-	down_write(&params->cell->vl_sem);
+	volume = afs_lookup_volume(params, vldb);
 
-	/* is the volume already active? */
-	if (vlocation->vols[params->type]) {
-		/* yes - re-use it */
-		volume = vlocation->vols[params->type];
-		afs_get_volume(volume);
-		goto success;
-	}
-
-	/* create a new volume record */
-	_debug("creating new volume record");
-
-	ret = -ENOMEM;
-	volume = kzalloc(sizeof(struct afs_volume), GFP_KERNEL);
-	if (!volume)
-		goto error_up;
+error:
+	kfree(vldb);
+	return volume;
+}
 
-	atomic_set(&volume->usage, 1);
-	volume->type		= params->type;
-	volume->type_force	= params->force;
-	volume->cell		= params->cell;
-	volume->vid		= vlocation->vldb.vid[params->type];
-
-	init_rwsem(&volume->server_sem);
-
-	/* look up all the applicable server records */
-	for (loop = 0; loop < 8; loop++) {
-		if (vlocation->vldb.srvtmask[loop] & (1 << volume->type)) {
-			server = afs_lookup_server(
-			       volume->cell, &vlocation->vldb.servers[loop]);
-			if (IS_ERR(server)) {
-				ret = PTR_ERR(server);
-				goto error_discard;
-			}
+/*
+ * Destroy a volume record
+ */
+static void afs_destroy_volume(struct work_struct *work)
+{
+	struct afs_volume *volume = container_of(work, struct afs_volume, destructor);
+	struct afs_server_list *slist = rcu_access_pointer(volume->servers);
 
-			volume->servers[volume->nservers] = server;
-			volume->nservers++;
-		}
-	}
+	_enter("%p", volume);
 
-	/* attach the cache and volume location */
 #ifdef CONFIG_AFS_FSCACHE
-	volume->cache = fscache_acquire_cookie(vlocation->cache,
-					       &afs_volume_cache_index_def,
-					       volume, true);
+	ASSERTCMP(volume->cache, ==, NULL);
 #endif
-	afs_get_vlocation(vlocation);
-	volume->vlocation = vlocation;
 
-	vlocation->vols[volume->type] = volume;
+	afs_detach_volume_from_servers(volume, slist);
+	afs_remove_volume_from_cell(volume);
+	afs_put_serverlist(volume->cell->net, slist);
+	afs_put_cell(volume->cell, afs_cell_trace_put_vol);
+	trace_afs_volume(volume->debug_id, volume->vid, refcount_read(&volume->ref),
+			 afs_volume_trace_free);
+	kfree_rcu(volume, rcu);
 
-success:
-	_debug("kAFS selected %s volume %08x",
-	       afs_voltypes[volume->type], volume->vid);
-	up_write(&params->cell->vl_sem);
-	afs_put_vlocation(vlocation);
-	_leave(" = %p", volume);
-	return volume;
-
-	/* clean up */
-error_up:
-	up_write(&params->cell->vl_sem);
-error:
-	afs_put_vlocation(vlocation);
-	_leave(" = %d", ret);
-	return ERR_PTR(ret);
-
-error_discard:
-	up_write(&params->cell->vl_sem);
-
-	for (loop = volume->nservers - 1; loop >= 0; loop--)
-		afs_put_server(volume->servers[loop]);
-
-	kfree(volume);
-	goto error;
+	_leave(" [destroyed]");
 }
 
 /*
- * destroy a volume record
+ * Try to get a reference on a volume record.
  */
-void afs_put_volume(struct afs_volume *volume)
+bool afs_try_get_volume(struct afs_volume *volume, enum afs_volume_trace reason)
 {
-	struct afs_vlocation *vlocation;
-	int loop;
-
-	if (!volume)
-		return;
+	int r;
 
-	_enter("%p", volume);
-
-	ASSERTCMP(atomic_read(&volume->usage), >, 0);
-
-	vlocation = volume->vlocation;
+	if (__refcount_inc_not_zero(&volume->ref, &r)) {
+		trace_afs_volume(volume->debug_id, volume->vid, r + 1, reason);
+		return true;
+	}
+	return false;
+}
 
-	/* to prevent a race, the decrement and the dequeue must be effectively
-	 * atomic */
-	down_write(&vlocation->cell->vl_sem);
+/*
+ * Get a reference on a volume record.
+ */
+struct afs_volume *afs_get_volume(struct afs_volume *volume,
+				  enum afs_volume_trace reason)
+{
+	if (volume) {
+		int r;
 
-	if (likely(!atomic_dec_and_test(&volume->usage))) {
-		up_write(&vlocation->cell->vl_sem);
-		_leave("");
-		return;
+		__refcount_inc(&volume->ref, &r);
+		trace_afs_volume(volume->debug_id, volume->vid, r + 1, reason);
 	}
+	return volume;
+}
 
-	vlocation->vols[volume->type] = NULL;
 
-	up_write(&vlocation->cell->vl_sem);
+/*
+ * Drop a reference on a volume record.
+ */
+void afs_put_volume(struct afs_volume *volume, enum afs_volume_trace reason)
+{
+	if (volume) {
+		unsigned int debug_id = volume->debug_id;
+		afs_volid_t vid = volume->vid;
+		bool zero;
+		int r;
+
+		zero = __refcount_dec_and_test(&volume->ref, &r);
+		trace_afs_volume(debug_id, vid, r - 1, reason);
+		if (zero)
+			schedule_work(&volume->destructor);
+	}
+}
 
-	/* finish cleaning up the volume */
+/*
+ * Activate a volume.
+ */
+int afs_activate_volume(struct afs_volume *volume)
+{
 #ifdef CONFIG_AFS_FSCACHE
-	fscache_relinquish_cookie(volume->cache, 0);
+	struct fscache_volume *vcookie;
+	char *name;
+
+	name = kasprintf(GFP_KERNEL, "afs,%s,%llx",
+			 volume->cell->name, volume->vid);
+	if (!name)
+		return -ENOMEM;
+
+	vcookie = fscache_acquire_volume(name, NULL, NULL, 0);
+	if (IS_ERR(vcookie)) {
+		if (vcookie != ERR_PTR(-EBUSY)) {
+			kfree(name);
+			return PTR_ERR(vcookie);
+		}
+		pr_err("AFS: Cache volume key already in use (%s)\n", name);
+		vcookie = NULL;
+	}
+	volume->cache = vcookie;
+	kfree(name);
 #endif
-	afs_put_vlocation(vlocation);
+	return 0;
+}
 
-	for (loop = volume->nservers - 1; loop >= 0; loop--)
-		afs_put_server(volume->servers[loop]);
+/*
+ * Deactivate a volume.
+ */
+void afs_deactivate_volume(struct afs_volume *volume)
+{
+	_enter("%s", volume->name);
 
-	kfree(volume);
+#ifdef CONFIG_AFS_FSCACHE
+	fscache_relinquish_volume(volume->cache, NULL,
+				  test_bit(AFS_VOLUME_DELETED, &volume->flags));
+	volume->cache = NULL;
+#endif
 
-	_leave(" [destroyed]");
+	_leave("");
 }
 
 /*
- * pick a server to use to try accessing this volume
- * - returns with an elevated usage count on the server chosen
+ * Query the VL service to update the volume status.
  */
-struct afs_server *afs_volume_pick_fileserver(struct afs_vnode *vnode)
+static int afs_update_volume_status(struct afs_volume *volume, struct key *key)
 {
-	struct afs_volume *volume = vnode->volume;
-	struct afs_server *server;
-	int ret, state, loop;
+	struct afs_server_list *new, *old, *discard;
+	struct afs_vldb_entry *vldb;
+	char idbuf[24];
+	int ret, idsz;
+
+	_enter("");
 
-	_enter("%s", volume->vlocation->vldb.name);
+	/* We look up an ID by passing it as a decimal string in the
+	 * operation's name parameter.
+	 */
+	idsz = snprintf(idbuf, sizeof(idbuf), "%llu", volume->vid);
 
-	/* stick with the server we're already using if we can */
-	if (vnode->server && vnode->server->fs_state == 0) {
-		afs_get_server(vnode->server);
-		_leave(" = %p [current]", vnode->server);
-		return vnode->server;
+	vldb = afs_vl_lookup_vldb(volume->cell, key, idbuf, idsz);
+	if (IS_ERR(vldb)) {
+		ret = PTR_ERR(vldb);
+		goto error;
 	}
 
-	down_read(&volume->server_sem);
+	/* See if the volume got renamed. */
+	if (vldb->name_len != volume->name_len ||
+	    memcmp(vldb->name, volume->name, vldb->name_len) != 0) {
+		/* TODO: Use RCU'd string. */
+		memcpy(volume->name, vldb->name, AFS_MAXVOLNAME);
+		volume->name_len = vldb->name_len;
+	}
 
-	/* handle the no-server case */
-	if (volume->nservers == 0) {
-		ret = volume->rjservers ? -ENOMEDIUM : -ESTALE;
-		up_read(&volume->server_sem);
-		_leave(" = %d [no servers]", ret);
-		return ERR_PTR(ret);
+	/* See if the volume's server list got updated. */
+	new = afs_alloc_server_list(volume, key, vldb);
+	if (IS_ERR(new)) {
+		ret = PTR_ERR(new);
+		goto error_vldb;
 	}
 
-	/* basically, just search the list for the first live server and use
-	 * that */
-	ret = 0;
-	for (loop = 0; loop < volume->nservers; loop++) {
-		server = volume->servers[loop];
-		state = server->fs_state;
-
-		_debug("consider %d [%d]", loop, state);
-
-		switch (state) {
-			/* found an apparently healthy server */
-		case 0:
-			afs_get_server(server);
-			up_read(&volume->server_sem);
-			_leave(" = %p (picked %08x)",
-			       server, ntohl(server->addr.s_addr));
-			return server;
-
-		case -ENETUNREACH:
-			if (ret == 0)
-				ret = state;
-			break;
-
-		case -EHOSTUNREACH:
-			if (ret == 0 ||
-			    ret == -ENETUNREACH)
-				ret = state;
-			break;
-
-		case -ECONNREFUSED:
-			if (ret == 0 ||
-			    ret == -ENETUNREACH ||
-			    ret == -EHOSTUNREACH)
-				ret = state;
-			break;
-
-		default:
-		case -EREMOTEIO:
-			if (ret == 0 ||
-			    ret == -ENETUNREACH ||
-			    ret == -EHOSTUNREACH ||
-			    ret == -ECONNREFUSED)
-				ret = state;
-			break;
-		}
+	write_lock(&volume->servers_lock);
+
+	discard = new;
+	old = rcu_dereference_protected(volume->servers,
+					lockdep_is_held(&volume->servers_lock));
+	if (afs_annotate_server_list(new, old)) {
+		new->seq = volume->servers_seq + 1;
+		rcu_assign_pointer(volume->servers, new);
+		smp_wmb();
+		volume->servers_seq++;
+		discard = old;
 	}
 
-	/* no available servers
-	 * - TODO: handle the no active servers case better
-	 */
-	up_read(&volume->server_sem);
+	/* Check more often if replication is ongoing. */
+	if (new->ro_replicating)
+		volume->update_at = ktime_get_real_seconds() + 10 * 60;
+	else
+		volume->update_at = ktime_get_real_seconds() + afs_volume_record_life;
+	write_unlock(&volume->servers_lock);
+
+	if (discard == old)
+		afs_reattach_volume_to_servers(volume, new, old);
+	afs_put_serverlist(volume->cell->net, discard);
+	ret = 0;
+error_vldb:
+	kfree(vldb);
+error:
 	_leave(" = %d", ret);
-	return ERR_PTR(ret);
+	return ret;
 }
 
 /*
- * release a server after use
- * - releases the ref on the server struct that was acquired by picking
- * - records result of using a particular server to access a volume
- * - return 0 to try again, 1 if okay or to issue error
- * - the caller must release the server struct if result was 0
+ * Make sure the volume record is up to date.
  */
-int afs_volume_release_fileserver(struct afs_vnode *vnode,
-				  struct afs_server *server,
-				  int result)
+int afs_check_volume_status(struct afs_volume *volume, struct afs_operation *op)
 {
-	struct afs_volume *volume = vnode->volume;
-	unsigned loop;
-
-	_enter("%s,%08x,%d",
-	       volume->vlocation->vldb.name, ntohl(server->addr.s_addr),
-	       result);
-
-	switch (result) {
-		/* success */
-	case 0:
-		server->fs_act_jif = jiffies;
-		server->fs_state = 0;
-		_leave("");
-		return 1;
-
-		/* the fileserver denied all knowledge of the volume */
-	case -ENOMEDIUM:
-		server->fs_act_jif = jiffies;
-		down_write(&volume->server_sem);
-
-		/* firstly, find where the server is in the active list (if it
-		 * is) */
-		for (loop = 0; loop < volume->nservers; loop++)
-			if (volume->servers[loop] == server)
-				goto present;
-
-		/* no longer there - may have been discarded by another op */
-		goto try_next_server_upw;
-
-	present:
-		volume->nservers--;
-		memmove(&volume->servers[loop],
-			&volume->servers[loop + 1],
-			sizeof(volume->servers[loop]) *
-			(volume->nservers - loop));
-		volume->servers[volume->nservers] = NULL;
-		afs_put_server(server);
-		volume->rjservers++;
-
-		if (volume->nservers > 0)
-			/* another server might acknowledge its existence */
-			goto try_next_server_upw;
-
-		/* handle the case where all the fileservers have rejected the
-		 * volume
-		 * - TODO: try asking the fileservers for volume information
-		 * - TODO: contact the VL server again to see if the volume is
-		 *         no longer registered
-		 */
-		up_write(&volume->server_sem);
-		afs_put_server(server);
-		_leave(" [completely rejected]");
-		return 1;
-
-		/* problem reaching the server */
-	case -ENETUNREACH:
-	case -EHOSTUNREACH:
-	case -ECONNREFUSED:
-	case -ETIME:
-	case -ETIMEDOUT:
-	case -EREMOTEIO:
-		/* mark the server as dead
-		 * TODO: vary dead timeout depending on error
-		 */
-		spin_lock(&server->fs_lock);
-		if (!server->fs_state) {
-			server->fs_dead_jif = jiffies + HZ * 10;
-			server->fs_state = result;
-			printk("kAFS: SERVER DEAD state=%d\n", result);
-		}
-		spin_unlock(&server->fs_lock);
-		goto try_next_server;
-
-		/* miscellaneous error */
-	default:
-		server->fs_act_jif = jiffies;
-	case -ENOMEM:
-	case -ENONET:
-		/* tell the caller to accept the result */
-		afs_put_server(server);
-		_leave(" [local failure]");
-		return 1;
-	}
+	int ret, retries = 0;
+
+	_enter("");
 
-	/* tell the caller to loop around and try the next server */
-try_next_server_upw:
-	up_write(&volume->server_sem);
-try_next_server:
-	afs_put_server(server);
-	_leave(" [try next server]");
+retry:
+	if (test_bit(AFS_VOLUME_WAIT, &volume->flags))
+		goto wait;
+	if (volume->update_at <= ktime_get_real_seconds() ||
+	    test_bit(AFS_VOLUME_NEEDS_UPDATE, &volume->flags))
+		goto update;
+	_leave(" = 0");
 	return 0;
+
+update:
+	if (!test_and_set_bit_lock(AFS_VOLUME_UPDATING, &volume->flags)) {
+		clear_bit(AFS_VOLUME_NEEDS_UPDATE, &volume->flags);
+		ret = afs_update_volume_status(volume, op->key);
+		if (ret < 0)
+			set_bit(AFS_VOLUME_NEEDS_UPDATE, &volume->flags);
+		clear_bit_unlock(AFS_VOLUME_WAIT, &volume->flags);
+		clear_bit_unlock(AFS_VOLUME_UPDATING, &volume->flags);
+		wake_up_bit(&volume->flags, AFS_VOLUME_WAIT);
+		_leave(" = %d", ret);
+		return ret;
+	}
+
+wait:
+	if (!test_bit(AFS_VOLUME_WAIT, &volume->flags)) {
+		_leave(" = 0 [no wait]");
+		return 0;
+	}
+
+	ret = wait_on_bit(&volume->flags, AFS_VOLUME_WAIT,
+			  (op->flags & AFS_OPERATION_UNINTR) ?
+			  TASK_UNINTERRUPTIBLE : TASK_INTERRUPTIBLE);
+	if (ret == -ERESTARTSYS) {
+		_leave(" = %d", ret);
+		return ret;
+	}
+
+	retries++;
+	if (retries == 4) {
+		_leave(" = -ESTALE");
+		return -ESTALE;
+	}
+	goto retry;
 }